JP2015531573A - Method and system for avoiding transitions between radio access technologies when a packet data network is not accessible - Google Patents

Abstract

A method and apparatus are provided for avoiding a UE attempting to attach to a RAT network when the RAT network is not available. In accordance with certain aspects, the UE may detect a situation where the RAT network is not available and may take a preemptive action to prevent the UE from attempting to acquire service on that RAT. For example, the UE may effectively remove the RAT from the list of supported RATs by sending a UE capability message indicating that the RAT is not supported, which is the UE's Network-initiated transitions can be prevented. The UE may also remove an unavailable RAT from the internal list of supported RATs, which may prevent UE initiated transitions to that RAT.

Description

Cross-reference of related applications

[0001] This patent application is assigned to the assignee of this application and is hereby incorporated by reference in its entirety in Indian Patent Application No. 4186 / CHE / 2012 filed October 8, 2012, which is hereby expressly incorporated by reference in its entirety. Claim priority.

[0002] Certain aspects of the present disclosure relate generally to wireless communications, and more specifically, when a packet data network (PDN) is not accessible, radio access technology (RAT). ) To a method and system for avoiding transitioning between.

[0003] Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging and broadcast services. These wireless communication networks may be multiple access networks that can support multiple users by sharing available network resources. Examples of such multiple access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, and single carrier FDMA ( SC-FDMA) network.

[0004] A wireless communication network may include a number of eNodeBs that can support communication for a number of user equipments (UEs). The UE may communicate with the eNodeB via the downlink and uplink. The downlink (or forward link) refers to the communication link from the eNodeB to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the eNodeB.

[0005] As wireless communication technology advances, the number of different radio access technologies being utilized is increasing. For example, many geographic regions are currently served by multiple wireless communication systems, each of which can utilize one or more different radio access technologies (RAT). In such systems, to increase UE versatility, there is a recent trend toward multi-mode UEs that can operate in a network using multiple different types of RATs. For example, the multi-mode UE includes a global system for mobile communication (GSM (registered trademark): Global System for Mobile Communications) or a universal mobile communication system (UMTS) system, as well as a long term evolution (LTE). It may be possible to work in a term evolution) system.

[0006] While enabling UEs to operate across systems with different RATs helps to increase service coverage, switching between such systems is subject to certain challenges, eg Due to different operating requirements.

[0007] Certain aspects of the present disclosure provide a method for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks. provide. This method is generally based at least in part on detecting the situation in which the UE cannot obtain service in the first RAT network and sending a message, at least in part. Including preventing the UE from attempting to attach to the first RAT network.

[0008] Certain aspects of the present disclosure provide an apparatus for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks. I will provide a. The apparatus generally detects a situation where the UE is unable to obtain service in the first RAT network and sends a message to cause the UE to perform a first operation based at least in part on the detection of that situation. It includes at least one processor configured to prevent attempting to attach to the RAT network.

[0009] Certain aspects of the present disclosure are directed to an apparatus for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks. I will provide a. The apparatus generally includes a means for detecting a situation in which the UE is unable to acquire service in the first RAT network, and a UE based on at least in part the detection of the situation by sending a message. Includes means for preventing from attempting to attach to the first RAT network.

[0010] Certain aspects of the present disclosure provide a program product for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks. I will provide a. The program product is generally based at least in part on detecting the situation by sending a message and instructions for detecting a situation in which the UE cannot acquire service in the first RAT network, A computer readable medium having instructions stored thereon for preventing the UE from attempting to attach to the first RAT network is provided.

[0011] Various aspects and features of the disclosure are described in further detail below.

[0012] In order that the above-described features of the present disclosure may be understood in detail, a more detailed description of what has been briefly summarized above may be had by reference to a plurality of aspects thereof, of which Some are illustrated in the accompanying drawings. The accompanying drawings, however, illustrate only certain specific aspects of the present disclosure, and therefore the description may be regarded as limiting its scope, as it may recognize other equally effective aspects. Note that this should not be done.
[0013] FIG. 1 illustrates an example wireless communication system in accordance with certain aspects of the present disclosure. [0014] FIG. 2 is a block diagram conceptually illustrating an example bearer architecture in a wireless communication system in accordance with certain aspects of the present disclosure. [0015] FIG. 3 is a block diagram conceptually illustrating an example eNodeB and an example UE configured in accordance with certain aspects of the present disclosure. [0016] FIG. 4 illustrates one exemplary method for avoiding transitioning between different RAT networks in accordance with certain aspects of the present disclosure. [0017] FIG. 5 illustrates a flow diagram for avoiding transitioning between different RAT networks, in accordance with certain aspects of the present disclosure. [0018] FIG. 6 illustrates an example call flow diagram corresponding to the example method of FIG. 5, in accordance with certain aspects of the present disclosure.

Detailed description

[0019] In some RAT networks, a UE registers with a service by a procedure known as an attach procedure. During this procedure, the UE's identifier (ID) is verified and used to confirm subscription to services such as packet switched (PS) data and voice services. Thus, the term attach generally refers to registering with a service in the network. In some cases, the attach procedure may fail, for example, when there is no packet data network (PDN) available to provide a particular service requested for the UE.

[0020] Aspects of the present disclosure may allow the UE to avoid attempting to access the first RAT network when detecting a condition indicating that the attach procedure will fail. . In some cases, this technique results in a simple transition to the second RAT network as a result if the PDN is not accessible (eg, the access point name (APN) of the PDN is blocked). It can be applied to prevent a transition (eg, reselection or handover) from the second RAT network to the first RAT network that would result in a transition back to. In accordance with aspects of this disclosure, the first RAT network may be an LTE network, while the second RAT network may be a GSM or Universal Mobile Telecommunications System (UMTS) network.

[0021] Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. However, this disclosure can be embodied in many different forms and should not be construed as limited to any particular structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, one of ordinary skill in the art will now disclose whether the scope of the present disclosure is implemented independently of any other aspect of the present disclosure, or implemented in combination therewith. It should be understood that any aspect of the present disclosure is intended to cover. For example, an apparatus may be implemented or a method may be implemented using any number of aspects described herein. In addition, the scope of the present disclosure is not limited to or in addition to the various aspects of the present disclosure described herein, or any such apparatus or feature implemented using other configurations, functions, or configurations and functions. Is intended to cover the way. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

[0022] The term "exemplary" is used herein to mean "serving as an example, instance or illustration". Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0023] Although particular embodiments are described herein, many variations and permutations of these embodiments are within the scope of the disclosure. Although benefits and advantages are noted for some of the preferred embodiments, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. Rather, aspects of the present disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are described in the following description of the preferred aspects and in the figures. It is illustrated as an example. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

[0024] The techniques described herein include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single carrier FDMA ( It can be used for various wireless communication networks such as SC-FDMA) networks and the like. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, and so on. UTRA includes wideband CDMA (W-CDMA (registered trademark)) and low chip rate (LCR). CDMA2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM). An OFDMA network may implement wireless technologies such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, and the like. UTRA, E-UTRA, and GSM are part of the Universal Mobile Telecommunication System (UMTS). Long Term Evolution (LTE) is an upcoming release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2).

[0025] Single carrier frequency division multiple access (SC-FDMA) is a transmission technique that utilizes single carrier modulation at the transmitter side and frequency domain equalization at the receiver side. SC-FDMA has similar performance as OFDMA systems and has essentially the same overall complexity as them. However, SC-FDMA signals have a lower peak-to-average power ratio (PAPR) due to their unique single carrier structure. SC-FDMA has drawn much attention, especially in uplink communications where lower PAPR greatly benefits mobile terminals in terms of transmit power efficiency. This is currently the working assumption for uplink multiple access schemes in 3GPP LTE and Evolved UTRA.

[0026] A base station ("BS") is a Node B, a radio network controller ("RNC"), an evolved Node B (eNodeB), a base station controller ("BSC"), a base transceiver station ("BTS"), Base station (“BS”), transceiver function (“TF”), wireless router, wireless transceiver, basic service set (“BSS”), extended service set (“ESS”), radio base station (“RBS”), or Any other term may be included, realized as, or known as.

[0027] User equipment (UE) may include an access terminal, subscriber station, subscriber unit, remote station, remote terminal, mobile station, user agent, user device, user equipment, user station, or some other terminology. Can be realized as them, or can be known as them. In some implementations, a mobile station is a cellular phone, cordless phone, session initiation protocol (“SIP”) phone, wireless local loop (“WLL”) station, personal digital assistant (“PDA”), wireless connection capability (wireless). a handheld device having a connection capability), a station (“STA”), or any other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein include a telephone (eg, a cellular phone or a smartphone), a computer (eg, a laptop), a portable communication device, a portable computing device (eg, a personal digital assistant), an entertainment device (Eg, a music or video device, or satellite radio), a global positioning system device, and can be incorporated into any other suitable device configured to communicate via wireless or wired media. In some aspects, the node is a wireless node. Such wireless nodes may provide connectivity for or to a network (eg, a wide area network such as the Internet or a cellular network), for example, via a wired or wireless communication link.

An example wireless communication system
[0028] FIG. 1 illustrates an example wireless communication system in accordance with certain aspects of the present disclosure. An evolved universal terrestrial radio access network (E-UTRAN) 120 may support LTE, user equipment (UE) 115, several evolved Node B (eNB) 105, and UE 115. May include other network entities that can support wireless communication.

[0029] As described in further detail below, the techniques presented herein avoid UE 115 attempting to access E-UTRAN network 120 when the packet data network (PDN) is not accessible. Can help. In some cases, PDNs may be temporarily unavailable, or access point names (APNs) used to identify these PDNs may be blocked. As used herein, an APN is said to be blocked when an attach request for that APN is denied. In such a case, the APN is temporarily blocked for the time period specified in the reject message.

[0030] Each eNB 105 may provide communication coverage for a particular geographic region. The term “cell” can refer to a coverage area of an eNB and / or an eNB subsystem serving this coverage area. A serving gateway (S-GW) 124 may communicate with the E-UTRAN 120 to initiate packet routing and forwarding, mobility anchoring, packet buffering, and network-triggered service. Various functions such as and the like may be performed. The mobility management entity (MME) 126 may communicate with the E-UTRAN 120 and the serving gateway 124, and performs various functions such as mobility management, bearer management, paging message distribution, security control, authentication, gateway selection, and the like. Can be implemented. Several network entities in LTE are publicly available “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); General Description (“ Evolved Universal 3GPP TS 36.300 entitled "Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description,") ".

[0031] A radio access network (RAN) 130 may support GSM and may include several base stations 132 and other multiple network entities that can support wireless communication for UEs. A mobile switching center (MSC) 134 can communicate with the RAN 130, supports voice services, provides routing for circuit-switched calls, and is served by the MSC 134 Mobility management may be performed for UEs located within. Optionally, an inter-working function (IWF) 140 may facilitate communication between the MME 126 and the MSC 134 (eg, for 1xCSFB).

[0032] E-UTRAN 120, serving gateway 124, and MME 126 may be part of LTE network 102. RAN 130 and MSC 134 may be part of GSM network 104. For simplicity, FIG. 1 shows only some network entities in the LTE network 102 and the GSM network 104. LTE and GSM networks may also include other network entities that may support various functions and services.

[0033] In general, any number of wireless networks may be deployed in a given geographic region. Each wireless network may support a particular RAT and may operate on one or more frequencies. RAT may also be referred to as radio technology, air interface, and so on. A frequency may also be referred to as a carrier, a frequency channel, etc. Each frequency may support a single RAT in a given geographic region to avoid interference between different RAT wireless networks (different RAT networks). A network that utilizes a particular RAT is also referred to herein as a RAT network, or simply a radio access network (RAN). Thus, RAN refers to a network, while RAT refers to the type of technology that the network uses.

[0034] The UE 115 may be stationary or mobile and may also be referred to as a mobile station, station, access terminal, subscriber unit, station, etc. UE 115 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, and so on.

[0035] Upon powering up, UE 115 may search for a wireless network from which it can receive communication services. If more than one RAT network is detected, the RAT network with the highest priority may be selected to serve the UE 115, which may be referred to as the serving RAT network. UE 115 may perform registration with the serving RAT network if necessary. UE 115 may then operate in a “connected mode” to actively communicate with the serving RAT network. Alternatively, UE 115 may operate in “idle mode” and camped on to a serving RAT network if active communication is not requested by UE 115.

[0036] UE 115 may be located within the coverage of multiple RATs and / or multiple frequency cells while in idle mode. For LTE, UE 115 may select a frequency and RAT to camp on based on the priority list. This priority list may include a set of frequencies, a RAT associated with each frequency, and a priority for each frequency. For example, the priority list may include three frequencies X, Y and Z. Frequency X may be used for LTE and may have the highest priority, frequency Y may be used for GSM and may have the lowest priority, and frequency Z may also be for GSM And may have an intermediate priority. In general, the priority list may include any number of frequencies for any set of RATs and may be specific for UE location. UE 115 may define a priority list when available, for example, at the highest priority LTE frequency and at a frequency for other RATs with lower priority, as shown in the example above. Can be configured to prefer LTE.

[0037] UE 115 may operate in idle mode as follows. UE 115 may identify all frequencies / RATs that it can find “appropriate” service cell coverage in normal situations or “acceptable” service cell coverage in emergency situations. UE 115 may then camp on the frequency / RAT having the highest priority among all identified frequencies / RATs. UE 115 determines whether (i) the frequency / RAT is no longer available at the received signal strength at a given threshold, or (ii) another frequency / RAT with higher priority reaches the appropriate signal strength. Until this time, it can remain camped on at this frequency / RAT. This operating behavior for UE 115 in idle mode is the publicly available “evolved universal terrestrial radio access (E-UTRA); user equipment (UE) procedure in idle mode (“ Evolved Universal Terrestrial Radio ”). 3GPP TS 36.304 entitled “Access (E-UTRA); User Equipment (UE) procedures in idle mode,”) ”.

[0038] UE 115 may be able to receive packet switched (PS) data services from LTE network 102 and may camp on LTE network 102 while in idle mode. The LTE network 102 may have limited or no support for voice-over-Internet protocol (VoIP) services, which may be the case for LTE network early deployments. Many. Due to the limited VoIP service support, the UE 115 can be transferred to another RAT network for a voice call. This transfer may be referred to as circuit-switched (CS) fallback. UE 115 may be forwarded to a RAT that can support voice services such as 1xRTT, WCDMA, GSM, UMTS, and so on. For call origination with CS fallback, UE 115 may initially be connected to a source RAT network (eg, LTE) that may not support voice services. The UE may initiate a voice call with this source RAT network and may be transferred to a different RAT network (eg, a target RAT network) that can support the voice call. For example, the UE may be transferred from the source RAT network to the target RAT network by higher layer signaling for various procedures such as redirection, connection release using PS handover, etc.

[0039] FIG. 2 is a block diagram conceptually illustrating an example bearer architecture in a wireless communication system 200, in accordance with certain aspects of the present disclosure. The bearer architecture may be used to provide end-to-end service 235 between addressable peer entity 230 and UE 215 over a network.

[0040] Aspects of the present disclosure provide that a UE accesses a first RAT network when an end-to-end service 235 or EPS bearer 240 is not available, eg, when a packet data network (PDN) 210 is not accessible. Provide techniques that can be used to avoid trying. In some cases, PDN 210 may be temporarily unavailable. In other cases, the access point name (APN) used to identify the PDN is blocked. The UE may detect such situations by the occurrence of non-zero back-off timers for each APN that is trying to attach.

[0041] Peer entity 230 may be a server, another UE, or another type of network-addressable device. End-to-end service 235 may forward data between UE 215 and the peer entity according to a set of characteristics (eg, QoS) associated with end-to-end service 235. End-to-end service 235 may be realized by at least UE 215, eNodeB 205, serving gateway (SGW) 220, packet data network (PDN) gateway (PGW) 225, and peer entity 230. UE 215 and eNodeB 205 may be components of Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 208, which is the air interface of the LTE / LTE-A system. Serving gateway 220 and PDN gateway 225 may be components of evolved packet core (EPC) 209, which is the core network architecture of the LTE / LTE-A system. Peer entity 230 may be an addressable node on PDN 210 that is communicatively coupled to PDN gateway 225.

[0042] End-to-end service 235 is implemented between evolved packet system (EPS) bearer 240 between UE 215 and PDN gateway 225 and between PDN gateway 225 and peer entity 230 via the SGi interface. Can be realized by an external bearer 245. The SGi interface may expose Internet Protocol (IP) or other network layer addresses from the UE 215 to the PDN 210.

[0043] The EPS bearer 240 may be an end-to-end tunnel defined for a particular QoS. Each EPS bearer 240 has a plurality of parameters, eg, QoS class identifier (QCI), allocation and retention priority (ARP), guaranteed bit rate (GBR), and a maximum total. It may be related to an aggregate maximum bit rate (AMBR). The QCI may be an integer that indicates a QoS class associated with a predefined packet forwarding treatment with respect to latency, packet loss, GBR, and priority. In certain instances, the QCI may be an integer from 1 to 9. ARP may be used by the eNodeB 205 scheduler to provide preemption priority in case of contention between two different bearers for the same resource. The GBR may specify separate downlink and uplink guaranteed bit rates. Certain QoS classes may be non-GBR such that no guaranteed bit rate is defined for bearers of those classes.

[0044] The EPS bearer 240 is an E-UTRAN radio access bearer (E-RAB) 250 between the UE 215 and the serving gateway 220, an S5 / S8 bearer 255 between the PDN gateway and the serving gateway 220 via the S5 or S8 interface. Can be realized. S5 refers to the signaling interface between the serving gateway 220 and the PDN gateway 225 in a non-roaming situation, and S8 refers to the analog signaling interface between the serving gateway 220 and the PDN gateway 225 in a roaming situation. . The E-RAB 250 may be realized by the radio bearer 260 between the UE 215 and the eNodeB 205 via the LTE-Uu air interface and by the S1 bearer 265 between the eNodeB and the serving gateway 220 via the S1 interface.

[0045] Although FIG. 2 illustrates a bearer hierarchy in the context of one example of an end-to-end service 235 between a UE 215 and a peer entity 230, certain multiple bearers are associated with the end-to-end service 235. It will be appreciated that it can be used to carry data that does not. For example, a radio bearer 260 or other type of bearer may be established to transmit control data between two or more entities, where the control data is not related to the end-to-end service 235 data.

[0046] FIG. 3 is a block diagram conceptually illustrating an example eNodeB 305 and an example UE 315 configured in accordance with certain aspects of the present disclosure. For example, UE 315 may be an example of UE 115 shown in FIG. 1 and may be able to operate according to aspects of this disclosure.

[0047] The base station 305 may be equipped with an antenna 334 _1-t , and the UE 315 may be equipped with an antenna 352 _1-r , where t and r are integers greater than or equal to one. At base station 305, base station transmit processor 320 may receive data from base station data source 312 and control information from base station controller / processor 340. Control information may be carried on PBCH, PCFICH, PHICH, PDCCH, etc. Data can be carried on PDSCH or the like. Base station transmit processor 320 may process (eg, encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. Base station transmit processor 320 may also generate reference symbols for PSS, SSS, and cell specific reference signals (RS), for example. A base station transmit (TX) multiple-input multiple-output (MIMO) processor 330 may perform spatial processing (eg, precoding) on the data symbols, control symbols, and / or reference symbols, where applicable, An output symbol stream may be provided to a modulator / demodulator (MOD / DEMOD) 332 _1-t . Each base station modulator / demodulator 332 may process a respective output symbol stream (eg, for OFDM, etc.) to obtain an output sample stream. Each base station modulator / demodulator 332 may further process (eg, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulator / demodulators 332 _1-t may be transmitted via antennas 334 _1-t , respectively.

[0048] At UE 315, UE antenna 352 _1-r may receive the downlink signal from base station 305 and may provide the received signal to UE modulator / demodulator (MOD / DEMOD) 354 _1-r , respectively. . Each UE modulator / demodulator 354 may condition (eg, filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each UE modulator / demodulator 354 may further process input samples (eg, for OFDM, etc.) to obtain received symbols. UE MIMO detector 356 obtains the received symbols from all UE modulator / demodulators 354 _1-r , performs MIMO detection on the received symbols, if applicable, and implements the detected symbols Can do. UE receive processor 358 processes (eg, demodulates, deinterleaves, and decodes) the detected symbols, provides decoded data for UE 315 to UE data sink 360, and provides decoded control information to the UE controller / May be provided to the processor 380.

[0049] For the uplink, at UE 315, UE transmit processor 364 receives and processes data from UE data source 362 (eg, regarding PUSCH) and control information from UE controller / processor 380 (eg, regarding PUCCH). Can do. UE transmit processor 364 may also generate reference symbols for the reference signal. The symbols from UE transmit processor 364 may be precoded by UE TX MIMO processor 366, where applicable, and further processed by UE modulator / demodulator 354 _1-r (eg, for SC-FDM, etc.) 305 may be transmitted. At base station 305, the uplink signal from UE 315 is received by base station antenna 334, processed by base station modulator / demodulator 332, and, if applicable, detected by base station MIMO detector 336, and further Data and control information sent by UE 315 may be obtained that has been processed and decoded by receive processor 338. Base station receive processor 338 may provide decoded data to base station data sink 346 and may provide decoded control information to base station controller / processor 340.

[0050] Base station controller / processor 340 and UE controller / processor 380 may direct the operation at base station 305 and UE 315, respectively. Base station controller / processor 340 and / or other processors and modules at base station 305 may perform or direct the execution of various processes, for example, with respect to the techniques described herein. Other processors and modules in UE controller / processor 380 and / or UE 315 may also perform or direct the execution of other processes related to, for example, the functional blocks illustrated in FIGS. 4 and 5 and / or the techniques described herein. Can do. Base station memory 342 and UE memory 382 may store data and program codes for base station 305 and UE 315, respectively. A scheduler 344 may schedule UE 315 for data transmission on the downlink and / or uplink.

Exemplary techniques for avoiding transitions between RATs when the PDN is not accessible
[0051] In LTE, a UE needs to register with a network in order to receive a certain plurality of services by a procedure called a network attachment (or attach procedure). This attach procedure enables IP connectivity for the UE by establishing a default EPS bearer. In some cases, the attach procedure may also trigger a procedure for establishing one or more dedicated EPS bearers for that UE. If the UE cannot activate the default bearer in LTE, the UE cannot receive service via LTE and the UE may need to access another radio access technology (RAT) network to receive the service .

[0052] As noted above, certain aspects of the present disclosure may provide for a UE to communicate between multiple RATs when the UE cannot obtain service on one of the multiple RATs such as LTE and UMTS. Provides a technique that can help to avoid being switched. For example, such a situation can occur due to temporary limitations at all designated protocol data network (PDN) attach gateways associated with the RAT network. During this temporary restriction, the UE is blocked from using the APN associated with the PDN attach gateway.

[0053] In LTE, UEs are restricted from using their “attached APNs” to register with the RAT network, and when all attached APNs are blocked, the UE cannot register with the RAT network. . As mentioned above, when an attach request for an APN is rejected, the APN is said to be blocked, typically during the time period specified in the reject message (eg, by a timer referred to as a T3396 timer). Blocked. The UE is not allowed to attempt an attach procedure using its APN during this defined “backoff” time.

[0054] Aspects of this disclosure recognize the situation where all attached APNs are blocked and take action to prevent the UE from attempting to register with the corresponding RAT network. To the UE. As described above, the UE may be able to detect a situation where all attached APNs have an active (non-zero) backoff timer.

[0055] In other RAT networks, eg, UMTS and GSM, there is no requirement to leave at least one bearer attached for service coverage. Thus, the UE may remain connected to the UMTS / GSM network for circuit switched (CS) services (“camp on”).

[0056] As described above, the APN is an identifier of a PDN that the UE desires to connect to. In a typical UE configuration, there is a set of APNs designated as “Attached APNs” for LTE. These APNs can be configured by the user or operator, and (if only their PDN is given a basic set of services, specify the attached APN), the basic set of services is only if that is provided to the UE, the UE can be used to help define a policy that can remain camped on to the full-service in the LTE (remain camped for).

[0057] If all attached APNs are blocked in LTE, the UE cannot perform an attach procedure when the UE tries to attach to the LTE network (eg, it can recognize the LTE network, but to the service The UE moves to the GSM / UMTS network. A conventional UE may acquire GSM or UMTS service and complete a successful registration for CS and PS domains with the operator network. Under certain multiple conditions (eg, if the reference signal measurements indicate better radio coverage), the UE may reselect LTE. This reselection may be initiated by the UE or by the operator network. In either case, the UE may attempt to reselect to the LTE network by sending a tracking area update (TAU) request. If there is an active PS call established in the GSM / UMTS network, the non-attached PDN may be available in LTE by reselection and the UE may successfully transition to the LTE network.

[0058] However, assuming there is no active PS call (either voice or data) (and no active PDP bearer), the LTE network requests that the UE perform an attach procedure (eg, (With cause code indicating reason for refusal). The cause code may be designed to prompt the UE to perform an attach procedure, in which case the UE blocks all attached APNs (eg, with an active backoff timer from a previous failed attempt). As a result, the attach procedure cannot be executed. Since it is not possible to acquire full service in LTE, the conventional UE acquires GSM / UMTS service again and repeats the above steps to rapidly transition (ping-pong) between GSM / UMTS and LTE network. It will be.

[0059] FIG. 4 illustrates an example method 400 for avoiding transitioning between different RAT networks in accordance with certain aspects of the present disclosure.

[0060] The method 400 begins at 402 by detecting a situation in which the UE is unable to attach to the first RAT network. As an example, a UE may detect a situation in an LTE network where the PDN is not accessible to the UE because it connects on the LTE network. In some cases, even if all attached APNs are blocked, if there is an active PS call (in another network), the UE may be able to attach to the LTE network. Thus, detection may also include detecting that there are no active PS calls in the second RAT network when all attached APNs are blocked.

[0061] The method 400 continues at 404 by preventing the UE from attempting to attach to the first RAT network in response to the detection. For example, the UE may inform the network that it does not support LTE (eg, by sending a message with UE capability information), thereby allowing the UE to connect to the LTE network. To avoid being instructed to do so. Alternatively or additionally, the UE may initiate a selection initiated by the LTE UE (eg, by temporarily updating a state variable to indicate that it does not support LTE) ( Actions may be taken to disable UE-initiated selection). Accordingly, these techniques attempt to wastefully attach the UE to the LTE network by efficiently removing LTE from the list of RATs supported by the UE when LTE is temporarily unavailable. Can prevent.

[0062] In some cases, for example, if the UE detects that a previously blocked attached APN is unblocked (eg, updated UE capability information). The UE may later re-enable support for LTE (by sending a message with As mentioned above, if there is an active PS call established in the GSM / UMTS network, the non-attached PDN may be available on LTE by reselection. Thus, the UE may also re-enable support for LTE upon establishment of an active PS call in a GSM / UMTS network.

[0063] FIG. 5 illustrates a flowchart 500 for avoiding transitioning between different RAT networks, in accordance with certain aspects of the present disclosure. At 502, the UE evaluates an APN designated for attaching to LTE (attached APN). For example, the UE may determine whether there is an APN with an inactive backoff timer. If there is an unblocked attach APN at the decision at 504 or there is an active PDP bearer (active PS call in GSM / UMTS), then the normal attach procedure is performed at 506 at the decision at 508 Can be done. Otherwise, the UE may temporarily disable LTE support at 510.

[0064] FIG. 6 illustrates an example call flow diagram illustrating a communication exchange between a UE 615, an LTE eNodeB 605, and a GSM / UMTS base station 632 that may operate in accordance with the techniques presented herein. Illustrate.

[0065] As illustrated, UE 615 may first register (camp on) at 602 with the GSM / UMTS network. The UE may then reselect the LTE network at 604, for example, if the reference signal measurements indicate better radio coverage in the LTE network. The illustrated example assumes that there are no active PS calls. As illustrated, the UE may attempt to attach to the LTE network (eg, via a tracking area update TAU), but this request uses the indication of the backoff timer for the corresponding APN, Can be rejected.

[0066] At 606, the UE determines that all attached APNs are blocked and disables LTE support. As illustrated, the UE may disable LTE support by sending a message with UE capability information indicating that LTE is not supported. This may prevent the UE from being redirected to the LTE network, even when the radio coverage in the LTE network is favorable.

[0067] As illustrated at 608, in some cases, the UE may re-enable support for LTE. For example, the UE may have attached APN (previously blocked) unblocked, or the presence of an active PS call established in the GSM / UMTS network (reattached on LTE by reselection) Meaning that a PDN may be available). The UE may send a message with updated UE capability information indicating support for LTE. This may again allow the UE to be redirected to the LTE network.

[0068] As described herein, aspects of this disclosure allow a UE to disable support for a given RAT network in response to detecting that the RAT network is not available to the UE. Provide techniques that make it possible. As a result, the UE may prevent repetitive switching between RAT networks, which may improve the user experience.

[0069] Although these techniques are described herein in connection with a UE that is capable of communicating in LTE and 3G networks (GSM and / or UMTS), the techniques presented herein are diverse. It can be applied in different RAT networks.

[0070] The various operations of the methods described above may be performed by any suitable means capable of performing the corresponding function. These means include various hardware and / or software component (s) and / or modules (including but not limited to circuits, application specific integrated circuits (ASICs) or processors). One or more). In general, if there are operations illustrated in the figures, those operations may have corresponding counterpart means-plus-function components having similar numbers.

[0071] As used herein, the term "determining" includes a wide variety of actions. For example, “determining” means calculating, calculating, processing, deriving, examining, examining (eg examining a table, database, or another data structure), verifying, etc. Can be included. Also, “determining” can include receiving (eg, receiving information), accessing (eg, accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing and the like.

[0072] As used herein, a phrase referring to a list of items "at least one of" refers to any combination of those items that includes a single element. By way of example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc Yes.

[0073] Various operations of the methods described above may be performed by various hardware and / or software component (s), circuits, and / or module (s). It can be implemented by any suitable means that can be implemented. In general, any operation illustrated in the figures may be performed by corresponding functional means capable of performing the operation.

[0074] Various exemplary logic blocks, modules and circuits described in connection with the present disclosure include general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate array signals (FPGAs). ), Or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. obtain. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be a combination of computing devices, eg, a combination of a DSP and one microprocessor, a plurality of microprocessors, one or more microprocessors coupled to a DSP core, or any other such configuration. Can also be implemented.

[0075] The algorithm or method steps described in connection with this disclosure may be implemented directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used are random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM® memory, registers, hard disk, removable disk, CD-ROM, etc. including. A software module may include a single instruction or many instructions and may be distributed across several different code segments, between different programs, and across multiple storage media. A storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.

[0076] The methods disclosed herein comprise one or more steps or actions for achieving the described method. These method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions may be changed without departing from the scope of the claims.

[0077] The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a computer-readable medium. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer readable media can be RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage device, or instructions or data structures Any other medium that can be used to carry or store the desired program code in form and that can be accessed by a computer can be provided. As used herein, (disk) and disc (disc) are compact disc (CD), laser disc (registered trademark), optical disc, digital multipurpose disc (DVD), floppy disc, and Blu-ray (registered). (Trademark) disc, in which case the disc normally reproduces data magnetically, while the disc reproduces data optically using a laser.

[0078] Accordingly, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored thereon (and / or encoded) for performing the operations described herein. It can be executed by one or more processors. For certain aspects, the computer program product may include packaging material.

[0079] Software or instructions may also be transmitted over a transmission medium. For example, software may use coaxial technology, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio and microwave from websites, servers, or other remote sources. When transmitted, coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio and microwave are included in the definition of transmission media.

[0080] Further, modules and / or other suitable means for performing the methods and techniques described herein may be downloaded if applicable and / or otherwise mobile. It should be understood that it can be obtained by a station and / or a base station. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, the various methods described herein allow mobile stations and / or base stations to store storage means (eg, physical storage media such as RAM, ROM, compact disk (CD) or floppy disk, etc.). It can be provided by the storage means so that various methods can be obtained in providing or combining. Moreover, any other suitable technique for providing the devices with the methods and techniques described herein may be utilized.

[0081] It is to be understood that the claims herein are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

[0082] While the foregoing is directed to aspects of the present disclosure, other aspects of the present disclosure and further aspects of the disclosure may be devised without departing from the basic scope thereof, As determined by the following claims.

[0082] While the foregoing is directed to aspects of the present disclosure, other aspects of the present disclosure and further aspects of the disclosure may be devised without departing from the basic scope thereof, As determined by the following claims.
The scope of claims at the beginning of the present application is appended below.
[C1] A method for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks, comprising:
Detecting a situation where the UE is unable to attach to the first RAT network;
Preventing the UE from attempting to attach to the first RAT network based at least in part on the detection of the situation by sending a message
A method comprising:
[C2] Detecting that one or more packet data networks (PDNs) specified for the UE are not available for use to attach to the first RAT network The method of C1, comprising.
[C3] The detection
The C1 of C2, comprising, when attaching to the first RAT network, determining that one or more access point names (APNs) identifying the one or more PDNs are blocked from use. Method.
[C4] The method of C2, wherein the detecting further comprises determining whether a packet switched (PS) call is active in the second RAT network.
[C5] The method of C1, wherein preventing comprises disabling UE-initiated reselection from the second RAT network to the first RAT network.
[C6] The method of C1, wherein the message comprises a message with UE capability information from which indication of support for the first RAT has been deleted.
[C7] detecting that the UE can attach to the first RAT network;
In response, sending a message having UE capability information with indication of support for the first RAT;
The method of C6, further comprising:
[C8] Detecting that the UE can attach to the first RAT network;
An active packet switched (PS) call on the second RAT network;
The availability of one or more packet data networks (PDNs) designated for the UE for use to attach to the first RAT network that were not previously available;
The method of C7, comprising detecting at least one of:
[C9] The method of C1, wherein the first RAT network comprises a long term evolution (LTE) network.
[C10] The method of C9, wherein the second RAT network comprises at least one of a Global System for Mobile Communications (GSM) network or a Universal Mobile Telecommunications System (UMTS) network.
[C11] An apparatus for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks,
Detecting a situation where the UE is unable to attach to the first RAT network;
Preventing the UE from attempting to attach to the first RAT network based at least in part on the detection of the situation by sending a message
At least one processor configured to:
A memory coupled to the at least one processor;
An apparatus comprising:
[C12] The C11 comprising the situation where one or more packet data networks (PDNs) specified for the UE are not available for use to attach to the first RAT network. Equipment.
[C13] The situation is
The apparatus of C12, comprising a situation where one or more access point names (APNs) identifying the one or more PDNs are blocked from use when attaching to the first RAT network.
[C14] The apparatus of C12, wherein the situation further comprises a situation in which a packet switched (PS) call is not active in the second RAT network.
[C15] The apparatus of C11, wherein the at least one processor is further configured to disable UE-initiated reselection from the second RAT network to the first RAT network.
[C16] The apparatus of C11, wherein the message comprises a message having UE capability information with an indication of support for the first RAT removed.
[C17] the at least one processor is:
Detecting that the UE can attach to the first RAT network;
In response, sending a message having UE capability information with indication of support for the first RAT;
The device of C16, further configured to perform:
[C18] the at least one processor is
An active packet switched (PS) call on the second RAT network;
The availability of one or more packet data networks (PDNs) designated for the UE for use to attach to the first RAT network that were not previously available;
Configured to detect that the UE can attach to the first RAT network by detecting at least one of:
The apparatus according to C17.
[C19] The apparatus of C11, wherein the first RAT network comprises a long term evolution (LTE) network.
[C20] The apparatus of C19, wherein the second RAT network comprises at least one of a Global System for Mobile Communications (GSM) network or a Universal Mobile Telecommunications System (UMTS) network.
[C21] an apparatus for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks,
Means for detecting a situation where the UE is unable to attach to the first RAT network;
Means for preventing the UE from attempting to attach to the first RAT network based at least in part on the detection of the situation by sending a message;
An apparatus comprising:
[C22] The means for detecting detects that one or more packet data networks (PDNs) specified for the UE are not available for use to attach to the first RAT network The apparatus of C21, comprising means for:
[C23] The apparatus of C21, wherein the means for preventing comprises means for disabling UE-initiated reselection from the second RAT network to the first RAT network.
[C24] The apparatus of C21, wherein the message comprises a message having UE capability information in which indication of support for the first RAT has been deleted.
[C25] means for detecting that the UE is able to attach to the first RAT network;
In response, means for transmitting a message having UE capability information with indication of support for the first RAT;
The apparatus according to C24, further comprising:
[C26] A program product for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks,
Instructions for detecting a situation where the UE is unable to attach to the first RAT network;
Instructions for preventing the UE from attempting to attach to the first RAT network based at least in part on the detection of the situation by sending a message;
A program product comprising a computer-readable medium having stored therein.
[C27] detecting that the one or more packet data networks (PDNs) specified for the UE are not available for use to attach to the first RAT network A program product according to C26, comprising:
[C28] The program product of C26, wherein the preventing comprises disabling UE-initiated reselection from the second RAT network to the first RAT network.
[C29] The program product of C26, wherein the message comprises a message having UE capability information in which indication of support for the first RAT has been deleted.
[C30] The instructions are:
Instructions for detecting that the UE can attach to the first RAT network;
In response, the program product of C29, further comprising instructions for transmitting a message having UE capability information with an indication of support for the first RAT.

Claims (30)

A method for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks, comprising:
Detecting a situation where the UE is unable to attach to the first RAT network;
Preventing the UE from attempting to attach to the first RAT network based at least in part on the detection of the situation by sending a message.   The detecting comprises detecting that one or more packet data networks (PDNs) designated for the UE are not available for use to attach to the first RAT network; The method of claim 1. Detecting the
The method of claim 2, comprising, when attaching to the first RAT network, determining that one or more access point names (APNs) identifying the one or more PDNs are blocked from use. The method described.   The method of claim 2, wherein the detecting further comprises determining whether a packet switched (PS) call is active in the second RAT network.   The method of claim 1, wherein preventing comprises disabling UE initiated reselection from the second RAT network to the first RAT network.   The method of claim 1, wherein the message comprises a message having UE capability information with an indication of support for the first RAT removed. Detecting that the UE can attach to the first RAT network;
In response, the method further comprises: transmitting a message having UE capability information with indication of support for the first RAT. Detecting that the UE can attach to the first RAT network;
An active packet switched (PS) call on the second RAT network;
The availability of one or more packet data networks (PDNs) designated for the UE for use to attach to the first RAT network that were not previously available;
8. The method of claim 7, comprising detecting at least one of:   The method of claim 1, wherein the first RAT network comprises a long term evolution (LTE) network.   The method of claim 9, wherein the second RAT network comprises at least one of a Global System for Mobile Communications (GSM) network or a Universal Mobile Telecommunications System (UMTS) network. An apparatus for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks,
Detecting a situation where the UE is unable to attach to the first RAT network;
At least one processor configured to prevent the UE from attempting to attach to the first RAT network by transmitting a message based at least in part on the detection of the situation When,
And a memory coupled to the at least one processor.   12. The situation of claim 11, wherein the situation comprises a situation where one or more packet data networks (PDNs) designated for the UE are not available for use to attach to the first RAT network. apparatus. The situation is
13. The apparatus of claim 12, comprising a situation where one or more access point names (APNs) identifying the one or more PDNs are blocked from use when attaching to the first RAT network.   The apparatus of claim 12, wherein the situation further comprises a situation where a packet switched (PS) call is not active in the second RAT network.   The apparatus of claim 11, wherein the at least one processor is further configured to disable UE initiated reselection from the second RAT network to the first RAT network.     The apparatus of claim 11, wherein the message comprises a message having UE capability information from which indication of support for the first RAT has been deleted. The at least one processor comprises:
Detecting that the UE can attach to the first RAT network;
In response, the apparatus is further configured to: send a message having UE capability information with indication of support for the first RAT. The at least one processor comprises:
An active packet switched (PS) call on the second RAT network;
The availability of one or more packet data networks (PDNs) designated for the UE for use to attach to the first RAT network that were not previously available;
Configured to detect that the UE can attach to the first RAT network by detecting at least one of:
The apparatus of claim 17.   The apparatus of claim 11, wherein the first RAT network comprises a long term evolution (LTE) network.   20. The apparatus of claim 19, wherein the second RAT network comprises at least one of a Global System for Mobile Communications (GSM) network or a Universal Mobile Telecommunications System (UMTS) network. An apparatus for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks,
Means for detecting a situation where the UE is unable to attach to the first RAT network;
Means for preventing the UE from attempting to attach to the first RAT network based on at least in part on the detection of the situation by sending a message.   The means for detecting is for detecting that one or more packet data networks (PDNs) specified for the UE are not available for use to attach to the first RAT network. The apparatus of claim 21, comprising means.   The apparatus of claim 21, wherein the means for preventing comprises means for disabling UE-initiated reselection from the second RAT network to the first RAT network.   24. The apparatus of claim 21, wherein the message comprises a message having UE capability information with an indication of support for the first RAT removed. Means for detecting that the UE is able to attach to the first RAT network;
25. The apparatus of claim 24, further comprising: means for transmitting a message having UE capability information with indication of support for the first RAT. A program product for wireless communication by a user equipment (UE) capable of communicating in at least first and second radio access technology (RAT) networks,
Instructions for detecting a situation where the UE is unable to attach to the first RAT network;
A computer-readable medium storing instructions for preventing the UE from attempting to attach to the first RAT network based on at least in part on the detection of the situation by sending a message A program product comprising:   The detecting comprises detecting that one or more packet data networks (PDNs) designated for the UE are not available for use to attach to the first RAT network; 27. A program product according to claim 26.   27. The program product of claim 26, wherein the preventing comprises disabling UE initiated reselection from the second RAT network to the first RAT network.   27. The program product of claim 26, wherein the message comprises a message having UE capability information with an indication of support for the first RAT removed. The instructions are
Instructions for detecting that the UE can attach to the first RAT network;
30. The program product of claim 29, further comprising, in response, instructions for transmitting a message having UE capability information with an indication of support for the first RAT.

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